Registering adjustment for multi-color printing



March 17, 1964 R. RElNARTZ ETAL REGISTERING ADJUSTMENT FOR MULTI-COLORPRINTING 2 Sheets-Sheet 1 Filed April 3, 1962 L V: m "m x uw W. x M 4%W. w/ I n is 3 .E f. I A A 2 n L mu 1 GM L .B say/ 1 H u 1 n L H 5%M 1 uu w m w V 5 k 5 o i/ m I; 0 v mwm swirl Raw. w mkrwm vn s- 4 uwmm March1954 R. REINARTZ ETAL REGISTERING ADJUSTMENT FOR MULTI-COLOR PRINTING 2Sheets-Sheet 2 Filed April 5, 1962 United States Patent 3,125,022REGESTERENG ADJUSTMENT FGR MULTI-COLOR PING Robert Reinartz and HermannFischer, Augsburg, Germany, assignors to MaschinenfabrikAugsburg-Numherg A. G., Augsburg, Germany, a corporation of GermanyFiied Apr. 3, 1962, Ser. No. 184,901 Claims priority, applicationGermany May 6, 1961 Claims. (Cl. 1tl1183) This invention relates tomulti-color printing on sheetfed multi-color printing presses and, moreparticularly, to an arrangement having adjustably displaceable sheetgripper mechanisms for selectively and controllably distorting sheets ofpaper being printed to compensate for opposite distortions of the sheetsduring printing which may adversely affect proper registration of thesuccessive images printed on each sheet to achieve the multi-colorprinted impression.

In multi-color printing where a final composite multicolor image isformed by the successive printing impressions of a plurality ofsuperimposed single color images, the fine quality of the finishedeffect depends to a large extent upon the precision and accuracy withwhich the several successively printed individual impressions or imagesare registered or congruent to form the composite multi-colored image.With sheet-fed multi-color presses and especially those having a largenumber of separate successive printing units, however, dimensionalvariations in the paper sheets being printed may occur during theprinting run, as caused by changes in moisture content of the paper(especially with lithographic printing) or other factors. Thus,regardless of the care with which the various printing plates arepositioned at the various printing stations to contact the sheets ofpaper over precisely the same area to provide exact registration of theseveral superimposed images or impressions, dimensional variations ordistortions of the paper sheet, such as may be caused by swelling of thecellulose fibers with variations in moisture content, may causedistortions of the registration of the several superimposed impressionsduring the actual printing thereof.

If it is attempted to correct or compensate for such dimensionalvariations in the sheets of paper or other material to be printed asbydistorting the sheet at the sheet feeding mechanism before the firstprinting unit, satisfactory or complete compensation may not be achievedthroughout the passage of the sheet through all the subsequent printingunits. For example, some compensatory control may be achieved for thefirst printing unit'by providing a control flap or lever for bowing thecenter of the sheet at the original sheet feeder, or by otherwisearranging for the sheet to be non-uniformly introduced into the firstprinting unit, but even if satisfactory compensation is secured at thefirst unit, the normal slippages, etc., in the sheet gripping mechanismsof other units may preclude similar compensatory distortion of the sheetthere.

Similarly, attempting to feed the sheets non-uniformly into sheetgrippers arranged on a curve instead of in a straight line across thepress and before the first printing unit may produce some compensatorydeforming of the sheets, but only with relatively thin paper and notwhen heavier paper sheets are being used. Especially with a large numberof sequential printing units in the multi-color press, moisture-induceddistortions or dimensional variations may occur in the paper sheet todifferent extents and producing distortions in different directions asthe sheet progresses through the press, so that various means ofattempting to compensate for such distortions at the sheet feeding endof the press may not produce satisfactory or individually controllableresults ice multi-color image desired when the printing of the sheet isfinished.

According to this invention, however, there is provided for deformingthe leading edge of the sheets at or immediately before each printingstation in multi-color printing presses, and in an individuallyadjustable manner, with such deformation being controllably provided inor opposite to the direction of sheet travel or transversely of thesheet, to stretch or warp or otherwise deform the sheet non-uniformly toa greater or less extent across the width thereof or otherwise as an aidin maintaining the impression area of the sheet in precise registrationfor the sequential printing impressions notwithstanding substantialdimensional variations in the sheet itself arising fromchanges inmoisture content or otherwise. Such effects may be provided inaccordance herewith as by arranging the rotating or reciprocating sheetgripping mechanism for each printing station so as to grip the leadingedge of the sheets and displace the center of the leading edge of thesheet in a manner which deforms the sheet to compensate for the abovedifficulties as the sheet is led into each printing station; and, as afurther feature of this invention, mechanism is provided whereby boththe extent and direction of such distortion of the center of the leadingedge of the sheet is individually controlled at each printing station asmay be required to produce the particular compensation desired at thatstation in the registering of the sequentially printed images orimpressions.

With the foregoing and additional objects in view, this invention willnow be described in more detail, and other objects and advantagesthereof will be apparent from the following description, theaccompanying drawings, and the appended claims.

In the drawings:

FIG. 1 is a partial front elevation, with some parts broken away orremoved, or part of the sheet gripper mechanism of a sheet-fed printingpress having this invention applied thereto;

FIG. 2 is a partial vertical section along the line 11-11 of FIG. 1;

FIG. 3 is a simplified diagrammatic or schematic view indicating furtheraspects of the operation of the mechanism of FIG. 1;

FIG. 4 is a detailed sectional view of a portion of the mechanism ofFIG. 2 and taken along the line IV-JV thereof; and

FIG. 5 is a partial top plan view on a somewhat larger scale of part ofthe mechanism of FIG. 1.

Referring to the drawings, in which like reference characters refer tolike parts throughout the several views thereof, an arrangement ofapparatus embodying and for practicing this invention is illustrated asbeing applied to the gripper mechanism in the impression cylinder forone printing station of a sheet-fed printing press, which mechanism isfor gripping the leading edge of a sheet of paper or other material tobe printed and carrying the sheet around the impression cylinder forprinting contact with a printing plate bearing against the sheet aroundthe impression cylinder during a portion of the rotation thereof. Sincesuch gripping mechanism in rotating impression cylinders is well knownand understood in this art, the drawings are primarily directed toillustrating the application of this invention to suchotherwisewellknown or conventional printing press arrangements, and manyof the constructional elements of the printing pressand the impressioncylinder have been omitted from the drawings for clarity and simplicity.It is also to be understood that this invention is applicable toswinging or reciprocating sheet gripping mechanisms operatingconventionally in association with the impression cylinder of asheet-fed printing press, notwithstanding that the particular embodimentillustrated is shown as applied to sheet gripping mechanism within or onthe impression cylinder.

Thus, a sheet of paper or other material to be printed is indicated atas overlying the impression surface of a printing press impressioncylinder 11 rotating in the direction of the arrow in FIG. 2, and withthe leading edge of sheet 10 gripped by sheet gripping mechanismincluding movable gripping fingers 12 for gripping the edge of the sheetagainst stationary gripping supports 13 mounted along gripper supportrail (15 in FIG. 2) extending axially across impression cylinder 11between the opposite ends thereof, all in known manner. Also, as will beunderstood, the opening and closing of gripper fingers 12 with respectto gripper supports 13 are cyclically effected and controlled byrotation of gripper shaft by the action of a cam arrangement (describedbelow) timed with the rotation of the impression cylinder 11 for thegripping and release of the leading edge of successive sheets 1t) duringthe printing operation.

As noted, since the illustrated embodiment relates to the sheet grippingmechanism mounted within a rotating impression cylinder, a main shaft21, carrying cylinder 11 and its associated mechanism, is mounted forrotation across the printing press and as, for example, journaled at 22in the opposite side Walls or supports of the press 23, whereby cylinder11 rotates during the press operation and sheets 14 to be printed aresequentially fed thereto to be gripped by grippers 12 and carried aroundthe surface of cylinder 11 for impression against the printing plate atthat particular printing station of the press.

In accordance herewith, the desired compensatory dis tortion of sheet 10is achieved by adjustably and selectively displacing the grippers 1213at the central portion of the sheet, rather than having all the grippersarranged and maintained in a straight axial line along cylinder 11. Thusthe gripper support rail 15 does not extend rigidly clear along cylinder11, but is provided in a plurality of articulated or hinged segments (asindicated in FIG. 3 and described in more detail below). In theillustrated embodiment, gripper support rail 15 is hinged or pivotedadjacent opposite ends of cylinder 11 as indicated at 25 and 26, as wellas being similarly hinged or articulated adjacent the center of thewidth of the printing press as indicated at 27 and 28, so that thegripper support rail clear across cylinder 11 is actually made up of acentral rigid segment 15, to which are hinged articulated segments 29and 30, each of which is in turn hinged, respectively at 25 and 26, tostationary gripper supporting rail segments 31 and 32 mounted atopposite ends of impression cylinder 11.

The central portion or segment 15 of the gripper support rail is mountedon carriage 35, as by bolts 86, and carriage 35 is in turn mounted forlimited sliding movement along the line of travel of sheet 10 throughthe printing press, as by rails 36 slidably engaging support ing races37 on radially extending supporting arms 38 of a bracket arrangement 39mounted centrally of cylinder 11 and, in the illustrated embodiment, onmain shaft 21 thereof.

The desired cyclical and adjustable sliding movement of carriage 35 onsupporting arms 38 (from left to right in FIG. 2 and up and down in FIG.3) is provided, in the illustrated embodiment, by a bifurcated swingingmember 45 engaging a roller 46 mounted between depending projections 47on carriage 35, and with bifurcated member 45 being mounted for rotationwith a control shaft :8, the cyclic and controlled rotation thereofbeing effected, as described below, from mechanism at the end ofcylinder 11. Thus, as apparent from the foregoing, the entire mechanismindicated in FIG. 2 is within and rail and, consequently, articulatedsegments 29 and 3t thereof pivoted to segment 15. Thus, depending uponthe movement or positioning of carriage 35 to the left or the right inFIG. 2, the central portion of the leading edges of sheets 10 gripped bygrippers 12-13 will be more or less distorted out of a straight line, ascompared with the conventional situation where all the grippers 12-43are rigidly aligned axially straight along impression cylinder 11 tohold the leading edge of sheet 10 uniformly along a straight line,instead of deforming the leading edge of the sheet to one extent oranother as carriage 35 and grippers 1213 moved thereby are misaligned toone extent or another with the stationary opposite end segments 31 and32 of the gripper support rail.

In order to accommodate such movement or misalignment of the variousstationary and articulated segments 31, 29, 15, 30, and 26 of thegripper support rail and to accomplish operation of gripper fingers 12with respect thereto notwithstanding such misalignments, articulation ofgripper shaft 26), the rotation of which controls operation of thegrippers 12, is also provided in accordance herewith. That is, in theillustrated embodiment, gripper shaft 20 includes adjacent the centerthereof and enclosed within carriage 35 self-aligning bearings indicatedby 50, in known manner, to provide for rotation of gripper shaft 20notwithstanding the misalignments therein depending upon the position ofcarriage 35.

The cyclic or intermittent rotation of gripper shaft 20, for the purposeof opening and closing grippers 12 against gripper supports 13 to engageand release the leading edge of sheets 10 as impression cylinder 11rotates, is provided, in generally conventional manner, as by camfollowers 55 engaging a cam surface 56 mounted beyond the ends ofcylinder 11 and, for example, on side frames 23 of the printing presswhereby, as well understood, gripper shaft 20 will be rotated in onedirection or the other for opening and closing gripper fingers 12' atpredetermined angular positions of impression cylinder 11. Because'ofthe articulated character of gripper shaft 26 in the self-aligningbearings 50 in carriage 35, however, such cam and cam followerarrangements 55--56 are duplicated at both sides of the printing pressand beyond both ends of impression cylinder 11.

The cyclic or controlling rotation of control shaft 4-8, providing forthe positioning of carriage 35 to the left or right of FIG. 2 at thevarious angular positions of cylinder 11, is effected in the illustratedembodiment by cam follower 60 engaging cam surface 61 mounted on boss 62in the side frame 23 of the printing press. A spring mechanism 63 isprovided in known manner to urge cam follower 60 against cam surface 61.Preferably, in order to adjust and control both the extent and cyclicperiod of the movement of carriage 35, cam surface 61 is provided as anindependently rotating element, driven by worm 65 meshing with worm gearteeth 66 to provide an infinitely variable drive or control (in knownmanner) whereby the rotation and angular positioning of cam surface 61can be both predetermined and altered during and independent of rotationof cylinder 11 to adjust and control momentarily andindividually foreach different printing station the period and degree of displacement ormisalignment of carriage 35 and the associated gripper fingers 12 andgripper supports 13 with respect to the axis of impression cylinder 11,as may be required from printing station to printing station because ofthe quality or heaviness of the paper sheets 10 being printed and/ orthe accumulated moistureinduced or other distortions thereof.

Operation of a printing press including the illustrated embodiment ofthis invention, and according to the foregoing, is further illustratedwith reference to the schematic or diagrammatic showing of FIG. 3. Thus,in the normal or conventional type of arrangement, the several grippers12 are axially aligned all along impression cylinder 11 across theprinting press, and are controlled, under the action of a gripper shaft2% and the cyclic or intermittent rotation thereof induced by camfollowers 55 reacting to the particular profile of cam surface 56 duringrotation of cylinder ll, to open and close and receive and release theleading edge of a sheet introduced in known manner thereinto and to gripthe sheet and carry it around the surface of impression cylinder 11 fora printing impression against the printing plate of the press. Inaccordance with this invention, by contrast, a selected andindividuallycontrolled or adjusted rotation of control shaft 48 displaces carriage35 out of axial alignment and, as illustrative, into the dot-dash lineposition indicated'in FIG. 3, whereby the grippers 12 nearest carriage35 and in the area of the lateraltcentral portion of the leading edge ofsheet '10 may move through va longer path than those of the grippers 12which are positioned more adjacent the ends of cylinder 11 and lateraledges of sheets 10.

That is, the leading edge of each sheet 10 is introduced to and grippedby all the grippers 12 with carriage 35 and the various segments 15,2930, and 31-32 of'the gripper support rail in axially aligned positionas indicated by the full lines in FIG. 3. Thereafter (as effected orpredetermined by the particular profiling of cam surface 61 and thevariable control drive 65-66 therefor) carriage 35 is moved more or lessout of alignment in whatever direction may be desired so as to deform orstretch or bow the leading edge of sheet 10 in a manner and to an extentat least partially compensatory of.whatever moisture-induced or otherdimensional variation the .sheet has undergone, so that the stretched ordeformed sheet is presented around the surface of impression cylinderlland for-a printing impression thereon in a manner to assure that theregistration of that particular printing impression, with previous andsubsequent sequential printing impressions, is achieved and received bysheet .10 in accurate registration to form the desired finishedcomposite image and notwithstanding the deformations ofthe paper.

As'will be apparent from the foregoing, perfect registration or any lackthereof is immediately observable during the press run with respect tothe impression provided by each printing station-on sheet 10. Therefore,with the foregoing arrangement, any necessary compensation can beprovided, by regulation as may be required to provide the extrastretching or distortion, merely by regulating the infinitely variabledrive 65-d6 of cam surface 61. Actually, if no distortion orcompensation therefor is required, the arrangement in accordanceherewith readily functions the same as any conventional sheet grippingmechanism 'andwith the grippers 1'2 and carriage 35 all axially aligned,as if they were rigidly supported, as in the full line position of FIG.3. Yet, with but a simple adjustment at each printing station as and ifand when required, carriage 35 is displaced in one way or the other sothat the various grippers 12 stretch the sheet 10 from the center in oneWay or the other (after having all gripped it in aligned position) sothat the sheet will be presented to receive its printed impression inprecise register, and notwithstanding the fact that the difference indistortion necessary at each of the printing stations of thernulti-color press may be different or that the dimensional variationsduring printing may vary from time to time for the same press run.

Thus there is provided in accordance herewith structures andarrangements (applicable either to sheet gripping mechanism builtconventionally into impression cylinders of sheet-fed presses or to thereciprocating or 6 chain-driven sheet grippers which feed sheets to suchimpression cylinders for individual printing stations) whereby apredetermined and constantly controlled and individually adjustabledistortion may be readily induced to each sheet presented individuallyat each printing station to compensate for or otherwise correct oradjust dimensional variations within the sheet or other necessaryperfections of the precise registering of that particular printedimpression so that the printed image coincides exactly as desired withthe previously or subsequently printed area of the sheet to obtain thedesired final composite multi-color printed image on the sheetnotwithstanding dimensional distortions or variations of the sheetoccasioned by moisture changes or other factors to which it is subjectedduring the printing process. Similarly, there is provided in accordancewith the foregoing for individual adjustment of such distortions orstretching or other control at each printing station and foraccommodating the particular characteristics of each press run includingvariations in performance of different grades or weights of paper aswell as variations between different printing stations on the sameprinting press, by distorting or stretching or otherwise compensatingfor the necessary changes at each printing station after the leadingedge of the sheet to be printed has been firmly gripped, and bydisplacing the various grippers across the impressioncylinder to stretchor deform the sheet to a greater or lesser extent with regard to bothlateral and longitudinal dimensional changes therein and withoutinterfering with either the speed or other factors of the normaloperation of the printing press whether or not the dimensional changesbeing compensated for occur uniformly among all the printing stationsand with various different types of sheet material being printed.

As apparent from the foregoing, the arrangements of apparatus providedin acordance'herewith are readily and simply supplied, even within arotating impression cylinder, and are similarly simply applicable, aswill be understood, to reciprocating or chain-driven sheet grippingmechanismfor feeding a particular printing station or otherwise forindividually and adjustably and controllably distorting sheet materialbeing fed to each individual printing station in a-multi-color press tocompensate for the aforementioned dimensional variations within thesheet which may affect the appropriate or optimumly desired preciseregistration of a plurality of superimposed printed impressions forminga composite multi-colored finished result.

While the arrangements of structures and apparatus herein describedconstitute preferred embodiments of the invention, it is to beunderstood that the invention is not limited to these precise structuresand apparatus, and that changes may be made therein without departingfrom the scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a sheet-fed multi-color printing press having a plurality ofprinting stations for sequential printing of superimposed images oncongruent areas of sheets fed through all said stations and having animpression cylinger at each said printing station for receiving saidsheets to be printed and for impression thereof against a printing plateat each said station and in which said sheets are susceptible todimensional variations and deformations during said printing of saidsequential images thereon, the combination which comprises a pluralityof sheet gripping means on said impression cylinder gripping the axiallyextending leading edge of each said sheet fed thereto, and including aplurality of said grippers spaced axially along said cylinder andnormally axially aligned with respect thereto, an articulated rail alongsaid cylinder with portions thereof independently movablecircumferentially thereof, means for mounting said sheet grippers alongsaid articulated rail, means for displacing selected portions of saidarticulated rail and said grippers mounted thereon into and out of axialalignment with said cylinder for distorting said leading edge of saidsheets effecting concomitant distorting of the area of said sheets to beprinted for compensating for said dimensional variations anddeformations thereof, said distortion of said sheets being positivelymaintained throughout substantially the entire passage of each saidsheet through each said printing station, and means for adjusting theextent and direction of said selective displacement of said articulatedrail and said grippers thereon for controlling the distortion of saidsheets to compensate for said dimensional variations and deformationsthereof during said printing at each said printing station.

2. Apparatus as recited in claim 1 in which said means for moving saidarticulated rail includes a central carriage, means for mounting saidcarriage in said impression cylinder for limited circumferentialmovement with respect to the surface thereof, and means in said cylinderfor moving said carriage to any of a plurality of differentcircumferential positions during continued rotation of said impressioncylinder about the axis thereof.

3. Apparatus as recited in claim 2 in which said means for moving saidcarriage includes variable speed drive means for controlling andadjusting said movement of said carriage cyclically during rotation ofsaid impression cylinder.

4. Apparatus as recited in claim 1 which also includes a gripper shaftextending along said cylinder for cyclically actuating all said grippersto grip said sheets and means for driving said shaft during rotation ofsaid impression cylinder about the axis thereof, said shaft beingaxially articulated for displacement into and out of axial alignmentalong said cylinder along with said articulated rail.

5. Apparatus as recited in claim 2 which also includes articulatedgripper shaft segments for actuating said grippers to grip said sheets,means beyond the end of said cylinder for driving said gripper shaftsegments, and bearing means on said carriage for rotatably supportingcentrally located ends of said gripper shaft segments in both axiallyaligned and misaligned positions thereof.

6. In a sheet-fed multi-color printing press having a plurality ofprinting stations for sequential printing of superimposed images oncongruent areas of sheets fed through all said stations and having animpression cylinder at each said printing station for receiving saidsheets to be printed and for impression thereof against a printing plateat each said station and in which said sheets are susceptible todimensional variations and deformations during said printing of saidsequential images thereon, the combination which comprises a pluralityof sheet gripping means on said impression cylinder gripping the axiallyextending leading edge of each said sheet fed thereto, and including aplurality of said grippers spaced axially along said cylinder andnormally axially aligned with respect thereto, an articulated rail alongsaid cylinder with portions thereof independently movablecircumferentially thereof, means for mounting said sheet grippers alongsaid articulated rail, means for displacing selected portions of saidarticulated rail and said grippers mounted thereon into and out of axialalignment with said cylinder for distorting said leading edge of saidsheets effecting concomitant distorting of the area of said sheets to beprinted for compensating for said dimentional variations anddeformations thereof, said distortion of said sheets being positivelymaintained throughout substantially the entire passage of each saidsheet through each said printing station, means for adjusting the extentand direction of said selective displacement of said articulated railand said grippers thereon for controlling the distortion of said sheetsto compensate for said dimensional variations and deformations thereofduring said printing at each said printing station, a gripper shaftextending along said cylinder for cyclically actuating all said grippersto grip said sheets, means for driving said gripper shaft duringrotation of said cylinder, said gripper shaft being axially articulatedto conform to circumferential movements of said articulated rail, andmeans for positively and circumferentially displacing said gripper shaftin accordance with said circumferential displacement of said articulatedrail.

7. Apparatus as recited in claim 6 in which said means for moving saidarticulated rail and said articulated gripper shaft includes an axiallycentral carriage, means for mounting said carriage in said impressioncylinder for limited circumferential movement with respect to thesurface thereof, and means in said cylinder for moving said carriage toany of a plurality of different circumferential positions duringcontinued rotation of said imperssion cylinder about the axis thereof.

8. Apparatus as recited in claim 7 in which said means for moving saidcarriage incluudes variable speed drive means for controlling andadjusting said movement of said carriage cyclically during rotation ofsaid impression cylinder.

9. Apparatus as recited in claim 1 in which said articulated railincludes a plurality of segments pivoted for displacement incircumferential directions about said cylinder and in which means foreffecting said circumferential displacement are disposed in saidcylinder intermediate the extreme ends thereof for selectivelydisplacing at least some of said gripper means according to saiddistortions and dimensional variations experienced by said sheetspassing through said printing stations.

10. Apparatus as recited in claim 9 in which generally centrallydisposed ends of segments of said articulated rail are mounted inswingable bearing engagement with said means for effecting saidcircumferential displacement.

References Cited in the file of this patent UNITED STATES PATENTS2,577,099 Albrecht Dec. 4, 1951

1. IN A SHEET-FED MULTI-COLOR PRINTING PRESS HAVING A PLURALITY OFPRINTING STATIONS FOR SEQUENTIAL PRINTING OF SUPERIMPOSED IMAGES ONCONGRUENT AREAS OF SHEETS FED THROUGH ALL SAID STATIONS AND HAVING ANIMPRESSION CYLINGER AT EACH SAID PRINTING STATION FOR RECEIVING SAIDSHEETS TO BE PRINTED AND FOR IMPRESSION THEREOF AGAINST A PRINTING PLATEAT EACH SAID STATION AND IN WHICH SAID SHEETS ARE SUSCEPTIBLE TODIMENSIONAL VARIATIONS AND DEFORMATIONS DURING SAID PRINTING OF SAIDSEQUENTIAL IMAGES THEREON, THE COMBINATION WHICH COMPRISES A PLURALITYOF SHEET GRIPPING MEANS ON SAID IMPRESSION CYLINDER GRIPPING THE AXIALLYEXTENDING LEADING EDGE OF EACH SAID SHEET FED THERETO, AND INCLUDING APLURALITY OF SAID GRIPPERS SPACED AXIALLY ALONG SAID CYLINDER ANDNORMALLY AXIALLY ALIGNED WITH RESPECT THERETO, AN ARTICULATED RAIL ALONGSAID CYLINDER WITH PORTIONS THEREOF INDEPENDENTLY MOVABLECIRCUMFERENTIALLY THEREOF, MEANS FOR MOUNTING SAID SHEET GRIPPERS ALONGSAID ARTICULATED RAIL, MEANS FOR DISPLACING SELECTED PORTIONS OF SAIDARTICULATED RAIL AND SAID GRIPPERS MOUNTED THEREON INTO AND OUT OF AXIALALIGNMENT WITH SAID CYLINDER FOR DISTORTING SAID LEADING EDGE OF SAIDSHEETS EFFECTING CONCOMITANT DISTORTING OF THE AREA OF SAID SHEETS TO BEPRINTED FOR COMPENSATING FOR SAID DIMENSIONAL VARIATIONS ANDDEFORMATIONS THEREOF, SAID DISTORTION OF SAID SHEETS BEING POSITIVELYMAINTAINED THROUGHOUT SUBSTANTIALLY THE ENTIRE PASSAGE OF EACH SAIDSHEET THROUGH EACH SAID PRINTING STATION, AND MEANS FOR ADJUSTING THEEXTENT AND DIRECTION OF SAID SELECTIVE DISPLACEMENT OF SAID ARTICULATEDRAIL AND SAID GRIPPERS THEREON FOR CONTROLLING THE DISTORTION OF SAIDSHEETS TO COMPENSATE FOR SAID DIMENSIONAL VARIATIONS AND DEFORMATIONSTHEREOF DURING SAID PRINTING AT EACH SAID PRINTING STATION.